Basic Reflection Support

[gkhanna79]

• Reflection metadata transform (transform ECMA metadata and type system entities to the native metadata format)
• Make sure reflection gets initialized at startup path
• Emit a mapping table between EETypes and native metadata
• Emit a mapping table between fields offsets and native metadata
• Emit a mapping table for methods
• Generate dynamic invoke stubs for reflection-invokable methods
• Clean out calls to System.Private.TypeLoader from System.Private.Reflection.Execution (this is not useful without __Canon instantiations anyway)

Out of scope (not "basic reflection"):

• reflection invoking virtual and interface methods
• reflection field get/set for GC static/threadstatic fields
• reflection blocking
• reflection on generic types/methods
• Array.CreateInstance
• Type.GetType search in current assembly
• Type.MakePointerType
• RuntimeMethodHandle/RuntimeFieldHandle

Known dependencies on other tasks:
#469, #274, #273, #272

[MichalStrehovsky]

"Basic reflection" is done.